Mini2440 DM9000 驱动分析（一）

Mini2440 DM9000 驱动分析（一）

硬件特性

Mini2440开发板上DM9000的电气连接和Mach-mini2440.c文件的关系：

PW_RST 连接到复位按键，复位按键按下，低电平触发重新初始化，初始化完成后5us后可以使用（The DM9000 is ready after 5us when this pin deasserted ）

CMD 连接到s3c2440 的ADD2 pin

INT 连接到s3c2440 的EINT7/GPF7，将中断控制端口

LINK_ACT 连接到网络接口的GLEDK pin，连接到LINK LED，这样网卡上面的灯才可以亮

LINK_O、WAKEUP、SPEED100# 这三个pin并联之后连接的网络接口的YLEDK pin

AEN 连接到s3c2440 的nGCS4/GPA15 pin

IOR# 连接到s3c2440 的nOE pin

IOW# 连接到s3c2440 的 nWE pin

IOWAIT 直接通过电阻借电源，即高电平

TXO-、TXO+、RX-、RX+ 直接接到网络端口用于数据收发

SD0-15 连接到s3c2440 的DATA0-15

其中片选信号AEN使用了nGCS4，所以网卡的内存区域在BANK4，也就是从地址0x20000000开始。

DM9000的TXD[2:0]作为strap pin在电路图中是空接的，所以IO base是300H。

中断使用了EINT7。

代码如下：

/* DM9000AEP 10/100 ethernet controller */
#define MACH_MINI2440_DM9K_BASE (S3C2410_CS4 + 0x300)

static struct resource mini2440_dm9k_resource[] = {
        [0] = {
                .start = MACH_MINI2440_DM9K_BASE,
                .end   = MACH_MINI2440_DM9K_BASE + 3,
                .flags = IORESOURCE_MEM
        },
        [1] = {
                .start = MACH_MINI2440_DM9K_BASE + 4,
                .end   = MACH_MINI2440_DM9K_BASE + 7,
                .flags = IORESOURCE_MEM
        },
        [2] = {
                .start = IRQ_EINT7,
                .end   = IRQ_EINT7,
                .flags = IORESOURCE_IRQ | IORESOURCE_IRQ_HIGHEDGE,
        }
};

/*
 *  * The DM9000 has no eeprom, and it's MAC address is set by
 *   * the bootloader before starting the kernel.
 *    */
static struct dm9000_plat_data mini2440_dm9k_pdata = {
        .flags          = (DM9000_PLATF_16BITONLY | DM9000_PLATF_NO_EEPROM),
};

static struct platform_device mini2440_device_eth = {
        .name           = "dm9000",
        .id             = -1,
        .num_resources  = ARRAY_SIZE(mini2440_dm9k_resource),
        .resource       = mini2440_dm9k_resource,
        .dev            = {
                .platform_data  = &mini2440_dm9k_pdata,
        },
};

研究net driver首先就要先了解一下网络驱动编写的一个基本架构

两个重要的结构体简单介绍：sk_buff和net_device

sk_buff

如果把网络传输看成是运送货物的话，那么sk_buff就是这个“货物”了，所有经手这个货物的人都要干点什么事儿，要么加个包装，要么印个戳儿等等。收货的时候就要拆掉这些包装，得到我们需要的货物（payload data）。没有货物你还运输什么呢？由此可见sk_buff的重要性了。

关于sk_buff的详细介绍和几个操作它的函数，参考：“linux内核sk_buff的结构分析” http://www.linuxidc.com/Linux/2011-07/39163.htm，写得非常明白了。赞一个~

net_device

又是一个庞大的结构体。好吧，我承认我从来就没有看全过这个结构体。它在内核中就是指代了一个网络设备。驱动程序需要在探测的时候分配并初始化这个结构体，然后使用register_netdev来注册它，这样就可以把操作硬件的函数与内核挂接在一起。

对于我们来说probe是一切一切的开始，看看dm9000驱动probe需要用要的结构体

board_info

/* Structure/enum declaration ------------------------------- */
typedef struct board_info {

	void __iomem	*io_addr;	/* Register I/O base address */
	void __iomem	*io_data;	/* Data I/O address */
	u16		 irq;		/* IRQ */

	u16		tx_pkt_cnt;
	u16		queue_pkt_len;
	u16		queue_start_addr;
	u16		queue_ip_summed;
	u16		dbug_cnt;
	u8		io_mode;		/* 0:word, 2:byte */
	u8		phy_addr;
	u8		imr_all;

	unsigned int	flags;
	unsigned int	in_suspend :1;
	int		debug_level;

	enum dm9000_type type;

	void (*inblk)(void __iomem *port, void *data, int length);
	void (*outblk)(void __iomem *port, void *data, int length);
	void (*dumpblk)(void __iomem *port, int length);

	struct device	*dev;	     /* parent device */

	struct resource	*addr_res;   /* resources found */
	struct resource *data_res;
	struct resource	*addr_req;   /* resources requested */
	struct resource *data_req;
	struct resource *irq_res;

	struct mutex	 addr_lock;	/* phy and eeprom access lock */

	struct delayed_work phy_poll;
	struct net_device  *ndev;

	spinlock_t	lock;

	struct mii_if_info mii;
	u32		msg_enable;

	int		rx_csum;
	int		can_csum;
	int		ip_summed;
} board_info_t;

其中有两个很重要的结构体 net_device 和 mii_if_info

mii_if_info

struct mii_if_info {
	int phy_id;
	int advertising;
	int phy_id_mask;
	int reg_num_mask;

	unsigned int full_duplex : 1;	/* is full duplex? */
	unsigned int force_media : 1;	/* is autoneg. disabled? */
	unsigned int supports_gmii : 1; /* are GMII registers supported? */

	struct net_device *dev;
	int (*mdio_read) (struct net_device *dev, int phy_id, int location);
	void (*mdio_write) (struct net_device *dev, int phy_id, int location, int val);
};

net_device

/*
 *	The DEVICE structure.
 *	Actually, this whole structure is a big mistake.  It mixes I/O
 *	data with strictly "high-level" data, and it has to know about
 *	almost every data structure used in the INET module.
 *
 *	FIXME: cleanup struct net_device such that network protocol info
 *	moves out.
 */

struct net_device
{

	/*
	 * This is the first field of the "visible" part of this structure
	 * (i.e. as seen by users in the "Space.c" file).  It is the name
	 * the interface.
	 */
	char			name[IFNAMSIZ];
	/* device name hash chain */
	struct hlist_node	name_hlist;
	/* snmp alias */
	char 			*ifalias;

	/*
	 *	I/O specific fields
	 *	FIXME: Merge these and struct ifmap into one
	 */
	unsigned long		mem_end;	/* shared mem end	*/
	unsigned long		mem_start;	/* shared mem start	*/
	unsigned long		base_addr;	/* device I/O address	*/
	unsigned int		irq;		/* device IRQ number	*/

	/*
	 *	Some hardware also needs these fields, but they are not
	 *	part of the usual set specified in Space.c.
	 */

	unsigned char		if_port;	/* Selectable AUI, TP,..*/
	unsigned char		dma;		/* DMA channel		*/

	unsigned long		state;

	struct list_head	dev_list;
	struct list_head	napi_list;

	/* Net device features */
	unsigned long		features;
#define NETIF_F_SG		1	/* Scatter/gather IO. */
#define NETIF_F_IP_CSUM		2	/* Can checksum TCP/UDP over IPv4. */
#define NETIF_F_NO_CSUM		4	/* Does not require checksum. F.e. loopack. */
#define NETIF_F_HW_CSUM		8	/* Can checksum all the packets. */
#define NETIF_F_IPV6_CSUM	16	/* Can checksum TCP/UDP over IPV6 */
#define NETIF_F_HIGHDMA		32	/* Can DMA to high memory. */
#define NETIF_F_FRAGLIST	64	/* Scatter/gather IO. */
#define NETIF_F_HW_VLAN_TX	128	/* Transmit VLAN hw acceleration */
#define NETIF_F_HW_VLAN_RX	256	/* Receive VLAN hw acceleration */
#define NETIF_F_HW_VLAN_FILTER	512	/* Receive filtering on VLAN */
#define NETIF_F_VLAN_CHALLENGED	1024	/* Device cannot handle VLAN packets */
#define NETIF_F_GSO		2048	/* Enable software GSO. */
#define NETIF_F_LLTX		4096	/* LockLess TX - deprecated. Please */
					/* do not use LLTX in new drivers */
#define NETIF_F_NETNS_LOCAL	8192	/* Does not change network namespaces */
#define NETIF_F_GRO		16384	/* Generic receive offload */
#define NETIF_F_LRO		32768	/* large receive offload */

/* the GSO_MASK reserves bits 16 through 23 */
#define NETIF_F_FCOE_CRC	(1 << 24) /* FCoE CRC32 */
#define NETIF_F_SCTP_CSUM	(1 << 25) /* SCTP checksum offload */
#define NETIF_F_FCOE_MTU	(1 << 26) /* Supports max FCoE MTU, 2158 bytes*/

	/* Segmentation offload features */
#define NETIF_F_GSO_SHIFT	16
#define NETIF_F_GSO_MASK	0x00ff0000
#define NETIF_F_TSO		(SKB_GSO_TCPV4 << NETIF_F_GSO_SHIFT)
#define NETIF_F_UFO		(SKB_GSO_UDP << NETIF_F_GSO_SHIFT)
#define NETIF_F_GSO_ROBUST	(SKB_GSO_DODGY << NETIF_F_GSO_SHIFT)
#define NETIF_F_TSO_ECN		(SKB_GSO_TCP_ECN << NETIF_F_GSO_SHIFT)
#define NETIF_F_TSO6		(SKB_GSO_TCPV6 << NETIF_F_GSO_SHIFT)
#define NETIF_F_FSO		(SKB_GSO_FCOE << NETIF_F_GSO_SHIFT)

	/* List of features with software fallbacks. */
#define NETIF_F_GSO_SOFTWARE	(NETIF_F_TSO | NETIF_F_TSO_ECN | NETIF_F_TSO6)

#define NETIF_F_GEN_CSUM	(NETIF_F_NO_CSUM | NETIF_F_HW_CSUM)
#define NETIF_F_V4_CSUM		(NETIF_F_GEN_CSUM | NETIF_F_IP_CSUM)
#define NETIF_F_V6_CSUM		(NETIF_F_GEN_CSUM | NETIF_F_IPV6_CSUM)
#define NETIF_F_ALL_CSUM	(NETIF_F_V4_CSUM | NETIF_F_V6_CSUM)

	/*
	 * If one device supports one of these features, then enable them
	 * for all in netdev_increment_features.
	 */
#define NETIF_F_ONE_FOR_ALL	(NETIF_F_GSO_SOFTWARE | NETIF_F_GSO_ROBUST | \
				 NETIF_F_SG | NETIF_F_HIGHDMA |		\
				 NETIF_F_FRAGLIST)

	/* Interface index. Unique device identifier	*/
	int			ifindex;
	int			iflink;

	struct net_device_stats	stats;

#ifdef CONFIG_WIRELESS_EXT
	/* List of functions to handle Wireless Extensions (instead of ioctl).
	 * See <net/iw_handler.h> for details. Jean II */
	const struct iw_handler_def *	wireless_handlers;
	/* Instance data managed by the core of Wireless Extensions. */
	struct iw_public_data *	wireless_data;
#endif
	/* Management operations */
	const struct net_device_ops *netdev_ops;
	const struct ethtool_ops *ethtool_ops;

	/* Hardware header description */
	const struct header_ops *header_ops;

	unsigned int		flags;	/* interface flags (a la BSD)	*/
	unsigned short		gflags;
        unsigned short          priv_flags; /* Like 'flags' but invisible to userspace. */
	unsigned short		padded;	/* How much padding added by alloc_netdev() */

	unsigned char		operstate; /* RFC2863 operstate */
	unsigned char		link_mode; /* mapping policy to operstate */

	unsigned		mtu;	/* interface MTU value		*/
	unsigned short		type;	/* interface hardware type	*/
	unsigned short		hard_header_len;	/* hardware hdr length	*/

	/* extra head- and tailroom the hardware may need, but not in all cases
	 * can this be guaranteed, especially tailroom. Some cases also use
	 * LL_MAX_HEADER instead to allocate the skb.
	 */
	unsigned short		needed_headroom;
	unsigned short		needed_tailroom;

	struct net_device	*master; /* Pointer to master device of a group,
					  * which this device is member of.
					  */

	/* Interface address info. */
	unsigned char		perm_addr[MAX_ADDR_LEN]; /* permanent hw address */
	unsigned char		addr_len;	/* hardware address length	*/
	unsigned short          dev_id;		/* for shared network cards */

	struct netdev_hw_addr_list	uc;	/* Secondary unicast
						   mac addresses */
	int			uc_promisc;
	spinlock_t		addr_list_lock;
	struct dev_addr_list	*mc_list;	/* Multicast mac addresses	*/
	int			mc_count;	/* Number of installed mcasts	*/
	unsigned int		promiscuity;
	unsigned int		allmulti;

	/* Protocol specific pointers */

#ifdef CONFIG_NET_DSA
	void			*dsa_ptr;	/* dsa specific data */
#endif
	void 			*atalk_ptr;	/* AppleTalk link 	*/
	void			*ip_ptr;	/* IPv4 specific data	*/
	void                    *dn_ptr;        /* DECnet specific data */
	void                    *ip6_ptr;       /* IPv6 specific data */
	void			*ec_ptr;	/* Econet specific data	*/
	void			*ax25_ptr;	/* AX.25 specific data */
	struct wireless_dev	*ieee80211_ptr;	/* IEEE 802.11 specific data,
						   assign before registering */

/*
 * Cache line mostly used on receive path (including eth_type_trans())
 */
	unsigned long		last_rx;	/* Time of last Rx	*/
	/* Interface address info used in eth_type_trans() */
	unsigned char		*dev_addr;	/* hw address, (before bcast
						   because most packets are
						   unicast) */

	struct netdev_hw_addr_list	dev_addrs; /* list of device
						      hw addresses */

	unsigned char		broadcast[MAX_ADDR_LEN];	/* hw bcast add	*/

	struct netdev_queue	rx_queue;

	struct netdev_queue	*_tx ____cacheline_aligned_in_smp;

	/* Number of TX queues allocated at alloc_netdev_mq() time  */
	unsigned int		num_tx_queues;

	/* Number of TX queues currently active in device  */
	unsigned int		real_num_tx_queues;

	/* root qdisc from userspace point of view */
	struct Qdisc		*qdisc;

	unsigned long		tx_queue_len;	/* Max frames per queue allowed */
	spinlock_t		tx_global_lock;
/*
 * One part is mostly used on xmit path (device)
 */
	/* These may be needed for future network-power-down code. */

	/*
	 * trans_start here is expensive for high speed devices on SMP,
	 * please use netdev_queue->trans_start instead.
	 */
	unsigned long		trans_start;	/* Time (in jiffies) of last Tx	*/

	int			watchdog_timeo; /* used by dev_watchdog() */
	struct timer_list	watchdog_timer;

	/* Number of references to this device */
	atomic_t		refcnt ____cacheline_aligned_in_smp;

	/* delayed register/unregister */
	struct list_head	todo_list;
	/* device index hash chain */
	struct hlist_node	index_hlist;

	struct net_device	*link_watch_next;

	/* register/unregister state machine */
	enum { NETREG_UNINITIALIZED=0,
	       NETREG_REGISTERED,	/* completed register_netdevice */
	       NETREG_UNREGISTERING,	/* called unregister_netdevice */
	       NETREG_UNREGISTERED,	/* completed unregister todo */
	       NETREG_RELEASED,		/* called free_netdev */
	       NETREG_DUMMY,		/* dummy device for NAPI poll */
	} reg_state;

	/* Called from unregister, can be used to call free_netdev */
	void (*destructor)(struct net_device *dev);

#ifdef CONFIG_NETPOLL
	struct netpoll_info	*npinfo;
#endif

#ifdef CONFIG_NET_NS
	/* Network namespace this network device is inside */
	struct net		*nd_net;
#endif

	/* mid-layer private */
	void			*ml_priv;

	/* bridge stuff */
	struct net_bridge_port	*br_port;
	/* macvlan */
	struct macvlan_port	*macvlan_port;
	/* GARP */
	struct garp_port	*garp_port;

	/* class/net/name entry */
	struct device		dev;
	/* space for optional statistics and wireless sysfs groups */
	const struct attribute_group *sysfs_groups[3];

	/* rtnetlink link ops */
	const struct rtnl_link_ops *rtnl_link_ops;

	/* VLAN feature mask */
	unsigned long vlan_features;

	/* for setting kernel sock attribute on TCP connection setup */
#define GSO_MAX_SIZE		65536
	unsigned int		gso_max_size;

#ifdef CONFIG_DCB
	/* Data Center Bridging netlink ops */
	struct dcbnl_rtnl_ops *dcbnl_ops;
#endif

#if defined(CONFIG_FCOE) || defined(CONFIG_FCOE_MODULE)
	/* max exchange id for FCoE LRO by ddp */
	unsigned int		fcoe_ddp_xid;
#endif
};

确实是如此庞大的一个结构体，让人畏惧的感觉，饭要一口一口吃啊O(∩_∩)O~

另外，还是认识一下另一个上面提到的庞大结构体吧，sk_buff

/**
 *	struct sk_buff - socket buffer
 *	@next: Next buffer in list
 *	@prev: Previous buffer in list
 *	@sk: Socket we are owned by
 *	@tstamp: Time we arrived
 *	@dev: Device we arrived on/are leaving by
 *	@transport_header: Transport layer header
 *	@network_header: Network layer header
 *	@mac_header: Link layer header
 *	@_skb_dst: destination entry
 *	@sp: the security path, used for xfrm
 *	@cb: Control buffer. Free for use by every layer. Put private vars here
 *	@len: Length of actual data
 *	@data_len: Data length
 *	@mac_len: Length of link layer header
 *	@hdr_len: writable header length of cloned skb
 *	@csum: Checksum (must include start/offset pair)
 *	@csum_start: Offset from skb->head where checksumming should start
 *	@csum_offset: Offset from csum_start where checksum should be stored
 *	@local_df: allow local fragmentation
 *	@cloned: Head may be cloned (check refcnt to be sure)
 *	@nohdr: Payload reference only, must not modify header
 *	@pkt_type: Packet class
 *	@fclone: skbuff clone status
 *	@ip_summed: Driver fed us an IP checksum
 *	@priority: Packet queueing priority
 *	@users: User count - see {datagram,tcp}.c
 *	@protocol: Packet protocol from driver
 *	@truesize: Buffer size
 *	@head: Head of buffer
 *	@data: Data head pointer
 *	@tail: Tail pointer
 *	@end: End pointer
 *	@destructor: Destruct function
 *	@mark: Generic packet mark
 *	@nfct: Associated connection, if any
 *	@ipvs_property: skbuff is owned by ipvs
 *	@peeked: this packet has been seen already, so stats have been
 *		done for it, don't do them again
 *	@nf_trace: netfilter packet trace flag
 *	@nfctinfo: Relationship of this skb to the connection
 *	@nfct_reasm: netfilter conntrack re-assembly pointer
 *	@nf_bridge: Saved data about a bridged frame - see br_netfilter.c
 *	@iif: ifindex of device we arrived on
 *	@queue_mapping: Queue mapping for multiqueue devices
 *	@tc_index: Traffic control index
 *	@tc_verd: traffic control verdict
 *	@ndisc_nodetype: router type (from link layer)
 *	@dma_cookie: a cookie to one of several possible DMA operations
 *		done by skb DMA functions
 *	@secmark: security marking
 *	@vlan_tci: vlan tag control information
 */

struct sk_buff {
	/* These two members must be first. */
	struct sk_buff		*next;
	struct sk_buff		*prev;

	struct sock		*sk;
	ktime_t			tstamp;
	struct net_device	*dev;

	unsigned long		_skb_dst;
#ifdef CONFIG_XFRM
	struct	sec_path	*sp;
#endif
	/*
	 * This is the control buffer. It is free to use for every
	 * layer. Please put your private variables there. If you
	 * want to keep them across layers you have to do a skb_clone()
	 * first. This is owned by whoever has the skb queued ATM.
	 */
	char			cb[48];

	unsigned int		len,
				data_len;
	__u16			mac_len,
				hdr_len;
	union {
		__wsum		csum;
		struct {
			__u16	csum_start;
			__u16	csum_offset;
		};
	};
	__u32			priority;
	kmemcheck_bitfield_begin(flags1);
	__u8			local_df:1,
				cloned:1,
				ip_summed:2,
				nohdr:1,
				nfctinfo:3;
	__u8			pkt_type:3,
				fclone:2,
				ipvs_property:1,
				peeked:1,
				nf_trace:1;
	__be16			protocol:16;
	kmemcheck_bitfield_end(flags1);

	void			(*destructor)(struct sk_buff *skb);
#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
	struct nf_conntrack	*nfct;
	struct sk_buff		*nfct_reasm;
#endif
#ifdef CONFIG_BRIDGE_NETFILTER
	struct nf_bridge_info	*nf_bridge;
#endif

	int			iif;
#ifdef CONFIG_NET_SCHED
	__u16			tc_index;	/* traffic control index */
#ifdef CONFIG_NET_CLS_ACT
	__u16			tc_verd;	/* traffic control verdict */
#endif
#endif

	kmemcheck_bitfield_begin(flags2);
	__u16			queue_mapping:16;
#ifdef CONFIG_IPV6_NDISC_NODETYPE
	__u8			ndisc_nodetype:2;
#endif
	kmemcheck_bitfield_end(flags2);

	/* 0/14 bit hole */

#ifdef CONFIG_NET_DMA
	dma_cookie_t		dma_cookie;
#endif
#ifdef CONFIG_NETWORK_SECMARK
	__u32			secmark;
#endif

	__u32			mark;

	__u16			vlan_tci;

	sk_buff_data_t		transport_header;
	sk_buff_data_t		network_header;
	sk_buff_data_t		mac_header;
	/* These elements must be at the end, see alloc_skb() for details.  */
	sk_buff_data_t		tail;
	sk_buff_data_t		end;
	unsigned char		*head,
				*data;
	unsigned int		truesize;
	atomic_t		users;
};

看到这是结构，让我深深感觉到彻底理清网卡驱动的编写还需要好好下一番功夫，莫要小看了它啊

下面会开始具体分析网卡驱动的整个probe过程，很关键的知识点。。。。